FROM COSTLY REJECTIONS TO ZERO DEFECTS: THREAD CHECK INC. CUSTOMER PARTNERSHIP ACHIEVES QUALITY EXCELLENCE

Executive Summary

AZR Manufacturing Company faced quality issues with threaded stainless-steel electronic components due to worn thread plug gages, resulting in costly rejections and delays. Thread Check Inc. proposed using their 3-Wire Thread Measuring System to monitor gage wear to eliminate using undersize thread plug gages and recommended the use of multiple thread plug gages along with modified oversized pitch diameters.

By implementing Thread Check's recommendations, AZR Manufacturing Company documented that their new gages lasted up to five times longer than standard gages, increased productivity, and eliminated part rejections. The 3-Wire Thread Measuring System played a vital role in ensuring the accuracy of their gages, resulting in significant time and cost savings for the company.

Case Study Highlights:

Type of Customer: AZR Manufacturing Company specializes in producing precision-machined components using automatic screw machines and CNC machines.

Type of Problem: Quality issues in threaded stainless-steel electronic components were caused by using worn thread plug gages, leading to costly rejections and delays.

How Thread Check Engaged: Thread Check Inc. and a third-party lab investigated and found defective threads under low limit specifications were being passed, causing a 3-week delay due to investigation, gage recalibration, and part reinspection.

Solutions Provided: Thread Check’s 3-Wire Thread Measuring System was recommended to monitor gage wear, implement multiple gages, and modifying pitch diameter on new gaging.

Results and Long Term Effect: The solution extended gage life fivefold, boosted productivity, eliminated part rejections, and saved $39 per gage calibration while reducing calibration lead times by 3 weeks.

Situation

AZR Manufacturing Company, a high-volume production machine shop, encountered quality issues with threaded stainless-steel electronic components. Their customers required them to use high Acceptable Quality Limit (AQL) level sampling inspection with Statistical Process Control (SPC). In certain cases, they needed to inspect 100% of critical dimensions, including internal and external threads. Tight screw threads might affect a product's ability to fit or assemble properly, potentially leading to failure, which could be safety-critical in industries such as aerospace and medical.

The situation worsened when the company's quality manager inspected 100% of the threads using a recently calibrated but heavily used thread plug gage. Despite passing inspection, the customer's receiving inspection department rejected the tight threads during sample inspection. Consequently, AZR Manufacturing Company received notification of the material discrepancy, leading to the rejection and return of three separate lots, totaling 3000 parts.

The worn thread plug gage was at the core of the problem, as it had been used through numerous work shift cycles and was no longer within its specified tolerance. This resulted in the passing of threads that were under low limit specifications, causing a series of rejections and returns. The company faced significant delays and potential damage to their reputation with their customer due to these quality issues.

Key Highlights

AZR Manufacturing Company faced quality issues with threaded stainless-steel electronic components, requiring high AQL sampling inspection and SPC.
The recently calibrated but heavily used thread plug gage led to the passing of threads under low limit specifications.
The customer's incoming inspection department rejected and returned three lots, totaling 3000 parts.
Worn thread plug gages caused delays and potential damage to the company's reputation with their customer.

Tactics

Thread Check Inc. developed a strategy to address AZR Manufacturing Company's quality issues related to worn thread plug gages. They proposed implementing the 3-Wire Thread Measuring System to monitor gage wear, ensuring their gages were not worn undersize.

Additionally, Thread Check Inc. advised having several thread plug gages onsite for various stages of production and inspection: one for in-process inspection, another for the final inspection, and a third as a master for comparison and reference inspection against heavily used gages.

Lastly, Thread Check Inc. recommended shifting the pitch diameter up by .0003” on the go member to provide a longer gage life without affecting part assembly or function. This adjustment would slightly tighten the Pitch Diameter (P.D.) allowance but would improve gage longevity and reduce the likelihood of using an undersized work plug gage.

The Plan

Implement the 3-Wire Thread Measuring System to monitor thread plug gage wear.
Have multiple thread plug gages onsite for various inspection stages (in-process, final, and master reference).
Shift the pitch diameter up by .0003” on the go member to extend gage life without affecting part assembly or function.
Monitor the first 3-4 threads of each go member before, during, and after shifts for data collection on wear patterns and to develop a preventative maintenance gage recall plan.

Action

Incorporating Thread Check's recommendations, AZR Manufacturing Company purchased a 3-Wire Thread Measuring System for a 36TPI thread, which included a base assembly micrometer stand with an adjustable platform, a set of holders, precision wires for a 36 TPI thread, and a 0-1” digital micrometer. This system allowed them to accurately monitor the wear on their thread plug gages and maintain quality control.

AZR Manufacturing Company also ordered new thread plug gages with modified P.D.s on the go member, following Thread Check's suggestion to shift the pitch diameter up by .0003”. This modification improved gage life and helped prevent quality discrepancies related to worn gages.

Results

After implementing Thread Check's recommendations and using the 3-Wire Thread Measuring System, AZR Manufacturing Company experienced significant improvements in quality control and productivity. The system allowed the company to measure pitch diameters quickly and accurately in threaded parts and thread plug gages while reducing measurement time.

By discarding undersized gages instead of sending them out for recalibration, the quality department was able to save an estimated $39 per gage in calibration and shipping charges, along with two-to-three weeks' lead times. The 3-Wire Thread Measuring System enabled users to locate with the single wire side and measure anywhere along the thread gage, precisely determining where the wear starts and stops.

AZR Manufacturing Company's decision to order new thread plug gages with modified P.D.s on the go member resulted in gages lasting up to 5 times longer than standard ones. This increased longevity led to higher productivity and avoided the time and cost involved in purchasing new gages, while also ensuring that the gage pitch diameter was well off the low limit.

As a result of the improved process control, the company was able to deliver parts with zero rejections in a matter of months. Starting from three major lot rejections totaling 9,000 pieces that required extensive reinspection and documentation, AZR Manufacturing Company made impressive strides toward optimizing their process control, ultimately benefiting from significant time and cost savings.

Key Results

Enhanced Repeatability and Reproducibility (R&R) and reduced measurement time using the 3-Wire Thread Measuring System.
Saved an estimated $39 per gage in calibration and shipping charges and eliminated two-to-three weeks' lead times.
New thread plug gages with modified P.D.s lasted up to 5 times longer than standard ones, increasing productivity and cost-efficiency.
Achieved zero-part rejections within a matter of months, significantly improving process control.
Reduced reinspection and documentation efforts, resulting in considerable time and cost savings.

Summary

AZR Manufacturing Company faced quality issues with threaded stainless-steel electronic components due to using worn thread plug gages, leading to costly rejections and delays. Thread Check Inc. proposed using their 3-Wire Thread Measuring System to monitor gage wear and maintain gages intolerance while recommending multiple thread plug gages with modified pitch diameter measurements. By implementing these recommendations, AZR Manufacturing Company significantly improved quality control, productivity, and cost-efficiency.

The company adopted the 3-Wire Thread Measuring System, which enhanced Repeatability and Reproducibility (R&R) and reduced measurement time over standard 3 wire measurement. They also saved an estimated $39 per gage in calibration and shipping charges by not sending out undersize gages for recalibration. The new thread plug gages with modified pitch diameters lasted up to five times longer than standard ones, contributing to increased productivity and cost savings.

As a result, AZR Manufacturing Company achieved zero-part rejections within months, greatly improving process control. This led to considerable reductions in reinspection and documentation efforts, generating substantial time and cost savings for the company.